Beta-halogenoethylsilanes as fruit abscission agents

ABSTRACT

wherein X is chlorine or bromine, Y represents chlorine and R1 and R2 are both methyl, or the radical -OR3 and each of the radicals R1, R2 and R3 independently represent alkyl radicals, or the group -COR4, wherein R4 stands for an alkyl radical.   The present invention relates to methods for the regulation of plant growth, especially for fruit abscission, acceleration of ripening and latex discharge. The active substances used in these methods correspond to the formula

United States Patent [1 1 Foery et a].

[451 Oct. 14, 1975 BETA-HAIJOGENOETHYLSILANES AS FRUIT ABSCISSION AGENTS [75] Inventors: Werner Foery, Basel; Hans Peter Fischer, Bottmingen, both of Switzerland [73] Assignee: Ciba-Geigy Corporation, Ardsley,

22 Filed: Feb. 15, 1974 21 App]. No.: 443,179

Related US. Application Data [63] Continuation-impart of Ser. No. 186,392, Oct. 4,

1971, abandoned.

OTHER PUBLICATIONS Boye et al., Studies in Silico Organic Compds. etc.,

(1952), J. Org. Chem. 17, pp. 1389-92 (1952).

Primary ExaminerGlennon I-I. I-Iollrah Attorney, Agent, or Firm-Harry Falber; Frederick H. Rabin [57] ABSTRACT The present invention relates to methods for the regulation of plant growth, especially for fruit abscission, acceleration of ripening and latex discharge. The tive substances used in these methods correspond to the formula wherein X is chlorine or bromine, Y represents ch10- rine and R and R are both methyl, or the radical -OR,, and each of the radicals R,, R and R independently represent alkyl radicals, or the group -COR wherein R stands for an alkyl radical.

6 Claims, N0 Drawings BETA-HALOGENOETI-IYLSILANES AS FRUIT ABSCISSION AGENTS RELATED APPLICATION:

This application is a continuation-in-part of copending application Ser. No. 186,392, filed Oct. 4, 1971, now abandoned.

The present invention relates to new processes for the regulation of plant growth by the use of ,B-halogenethyl-silanes as active substances.

The B-halogen-ethyl-silanes contained as active substances correspond to formula I:

wherein X represents chlorine or bromine, Y represents chlorine or the radical R R R and R represent independently of each other, alkyl radicals or the group COR wherein R stands for an alkyl or halogenalkyl radical.

By alkyl radicals in formula I are meant straightchain or branched radicals having 1 to 5 carbon atoms, such as, e.g. methyl, ethyl, n-propyl, isopropyl, n-butyl, or sec-butyl.

The B-halogen-ethyl-silanes of formula I affect in a varying manner the growth of parts of plants situated above and below the ground; they are not phytotoxic in the usual concentrations in which theyare applied, and have a low toxicity towards warm-blooded animals. The active substances produce no morphological changes or damage which would result in a withering of the plant. The compounds are not mutagenic. Their action differs from that of a herbicidal active substance and of a fertiliser. The action corresponds more to the effects which can be observed on application of ethylene to various parts of plants. It is known that also the plant itself produces, in various stages of development, ethylene to a varying extent, particularly before and during the ripening process of the fruits, and at the end of the vegetation period as the abscission of the fruit and leaves occurs. Since the regulation of ripening and of fruit and leeaf abscission by chemical substances is of the greatest commercial significance for the cultivation of fruit, citrus fruits, pineapples and cotton, compounds have been sought with which such effects might be obtained without damage being caused to the treated plants. Various classes of substances have thus meanwhile become knowon with which it was possible for certain of these effects, with regard to growth regulation, to be achieved; the sphere of action of these substances in no way corresponds, however, to that of ethylene.

Compounds which, under certain conditions, release ethylene are known. Such compounds are relatively unstable under the effects of weather, because they are very susceptible to hydrolysis; or they are phytotoxic. fi-Halogenfethyl-phosphonic acid derivatives are described in the South African Pat. No. 68.1036 as active substances regulating plant growth. These compounds decompose in and on the plant with the release of ethylene, and are therefore similar in action andrange of action to ethylene. By virtue of their very low stability, phosphonic acid derivatives are not able, however, to satisfy the demands made on them. As they are stable only in an acid medium, more precisely in a pH-range below 5, the active substance concentrates have to be stabilised by the addition of acids. This acid addition limits, however, the range of application of these active substances with regard to phytotoxic effects. Furthermore, the storage of such sensitive active substance concentrates presents difficulties.

Also known, as herbicidal active substances, are halogenalkyl-methyLsilanes, cp. U.S. Pat. Nos. 3,390,976 and 3,390,977 and J. K. Leasure et al., J. Med. Chem. 9, 949 (1966). B-Chloroethyl-tris- (alkoxy)-silanes and ,B-chloroethyl-acetoxy-dialkoxy silanes and B-chloroethyl-diacetoxy-alkoxy silanes have been produced by F..W. Boye et al., J. Org. Chem 16, 391 (1951), resp. 17, 1386 (1952).

The US. Pat. No. 3,183,076 describes a-chloroethylmethyldialkoxy-silanes, which can be used for the promotion of germination power, leaf abscission, etc.

The present invention relates to agents containing, as active substances, B-halogen-ethyl-silanes, the said agents having a stimulating or retarding effect on plant growth in the various stages of development of the plants. By virtue of the very good stability of the active substances of formula I, these agents must not contain, apart from the usual carriers, distributing agents, and stabilisers protecting against the effects of light and oxidation, any additional acid stabilising additive, and have therefore, an unlimited field of application. The vegetative plant growth and the germination power are influenced by the agents; and the blossom formation, the development of the fruit and the formation of separating tissues promoted. In the case of monocotyledons, an increase in tillering and branching was observed with a simultaneous reduction of growth in height. There was moreover a strengthening of the support tissues of the stalks in the case of the treated plants. The formation of undesirable side shoots is very greatly reduced on various types of plants. Furthermore, gum trees are stimulated to produce a greater latex discharge, an effect which is of great commercial importance. Tests have shown that the rooting of seedlings and cuttings, as well as the development of tubers in the case of potatoes, is promoted. In addition, there occurs a simultaneous aprouting of dormant rhizomes, which is particularly important in the case of various perennial weeds such as couchgrass, Johnson grass and cyperus, which can then be easily destroyed or suppressed by herbicides. The germination capacity of seeds such as, e.g. seed potatoes and legumes is promoted with low concentrations, and prevented with higher concentrations. Both these effects are commercially important. A control of the blossoming time and of the number of blossoms is possible in the case of many ornamental and cultivated plants. This effect is an especially important factor in connection with pineapples. If all the trees or shrubs blossom simultaneously, then the crops can be gathered within a comparatively short space of time. With regard to cucurbitaceae, there occurs a displacement of the blossom sex differentiation in favour of pisstillate flowers.

The active substances promote the development of abscission layers, particularly between stalks and petioles. Consequently, fruits of all kinds, e.g. apples, pears, peaches, tomatoes, bananas, prunes, pineapples, cherries, citrus fruits and, particularly oil fruits (olives) can be separated from the fruit stems manually or mechanically without the exertion of great force. Damage to foliage and branches, which results from shaking tress and shrubs or by plucking fruit, is largely avoided and production capacity increased. Tests have also shown that in the case of fruit trees, particularly peaches, there occurs a thinning of blossom and fruit.

The extent and the nature of the action are dependent on the most diverse factors, particularly on the time of application with regard to the stage of development of the plant, and on the application concentration. These factors vary, however, depending on the type of plant and on the desired effect. Thus, for example, plants of which the fruit is to be sold, or in some other way utilised, will be treated after blossoming or at an appropriate interval of time before the gathering of the crop. Application of the active substances is effected by the use of solid or liquid agents, these being applied to parts of plants above the ground, to the surface of the soil, as well as into the soil itself. The preferred method is the application to the parts of plants above the soil, for which purposes solutions or aqueous suspensions are most suitable. In addition to solutions and dispersions for the treatment of the growth substrate (soil), dusts, granulates and scattering agents are also suitable.

The plant growth regulating action of the active substances can often be positively influenced by the addition of organic or inorganic acids and bases (e.g. acetic acid or sodium carbonate).

The beta-halogen-ethyl silanes are generally produced by reaction of a beta-halogen-ethyltrichlorsilane of formula II X CI-I CI-I Si (Cl) with three equivalents of an acid of formula III:

R,fi-OH (III) or of a carboxylic acid anhydride of formula IV:

R.-c|-o-fi-R, (I

to give a compound of formula V:

and, optionally, by stepwise exchange of two or three of the radicals -0-fi-R,

by radicals of alcohols of the formulae VI, VII, VIII R OH R OH

(VII

R OH

If, in the starting compound of formula [I X represents bromine, also low molecular alkanols may be used for the exchange of the radicals -OCO-R in formula V.

X in formula II represents chlorine or bromine; R in formulae III and IV has the meaning given under formula I; and R R and R in formulae VI, VII and VIII have the meaning given under formula I.

As in the reaction according to the invention, the exchange of the 3 chlorine atoms of the starting compound of formula III occurs stepwise, it is clear that intermediates, i.e. dichloroand monochloro-silanes of formulae c1 x-cH, cH,-si

on, (a)

and

can be isolated during the synthesis or as impureties from the crude final product.

The process is preferably carried out in the presence of solvents and/or diluents which are inert to the reactants. Aprotic solvents are particularly suitable, such as, e.g. aliphatic and aromatic hydrocarbons e.g. hexane, cyclohexane, benzene, toluene, xylene, halogenated hydrocarbons such as chlorinated ethylene, carbon tetrachloride, chloroform, chlorobenzene, also ethers and ethereal compounds such as diethyl ether, tetrahydrofuran, etc..

To obtain a complete reaction, it is also possible for the alcohols, carboxylic acids and carboxylic acid anhydrides employed as reactants to serve, when used in excess, as solvents or diluents.

Furthermore, it can be necessary in some cases to add an acid-binding agent to the reaction mixture. Suitable for this purpose are, in particular, tertiary amines such as trialkylamines, e.g. triethylamine, pyridine and pyridine bases, dialkylanilines, etc..

The reaction temperatures are in the range of 0 to C; the reaction duration can be between a few minutes and several days, and depends to a great extent on the reactivity of the alcohols employed.

Compositions according to the invention are produced in a manner known per se by the intimate mixing and grinding of active substances of the general formula I with suitable carriers optionally with the addition of dispersing agents or solvents which are inert to the active substances.

Water-dispersible concentrates of active substance, i.e. wettable powders, pastes and emulsion concentrates, are active substance concentrates which can be diluted with water to obtain any desired concentration. They consist of active substance, carrier, optionally additives which stabilise the active substance, surfaceactive substances, and anti-foam agents and, optionally,

solvents. The concentration of active substance in these agents is 0.5 80%.

The wettable powders and pastes are obtained by the mixing and grinding of theactive substances and dispersing agents and pulverulent carriers, in suitable de vices, until homogeneity is attained. Suitable carriers are, e.g. the following:

kaolin, talcum, bole, loess, chalk, limestone, ground limestone, attaclay, dolomite, diatomaceous earth, precipitated silicic acid, alkaline-earth silicates, sodium and potassium aluminium silicates (feldspar and mica), calcium and magnesium sulphates, magnesium oxide, ground synthetic materials, fertilisers such as ammonium sulphate, ammonium phosphate, ammonium nitrate, urea, ground vegetable products such as bran, bark dust, sawdust, ground nutshells, cellulose powder, residues of plant extractions, active charcoal, etc., alone or in admixture with each other.

Suitable dispersing agents are, e.g. the following: condensation products of sulphonated naphthalene and sulphonated naphthalene derivatives with formaldehyde, condensation products of naphthalene or of naphthalene-sulphonic acids with phenol and formaldehyde, as well as alkali, ammonium and alkaline-earth metal salts of ligninsulphonic acid, also alkylarylsulphonates, alkali metal salts and alkaline-earth metal salts of dibutylnaphthalenesulphonic acid, fatty alcohol sulphates such as salts of sulphated hexadecanols, heptadecanols, octadecanols, and salts of sulphated fatty alcohol glycol ether, the sodium salt of oleyl methyl tauride, ditertiary acetylene glycols, dialkyl dilauryl ammonium chloride, and fatty acid alkali-metal and alkaline-earth metal salts.

To these mixtures may also be added additives stabilising the active substance, and/or non-ionic, anionactive and cation-active substances, which, for example, improve and adhesiveness of the active substances on plants and on parts of plants (adhesives and agglutinants), and/or ensure a better wettability (wetting agents). Suitable adhesives are, for example, the following: olein/lime mixture, cellulose derivatives (methyl cellulose, carboxymethyl cellulose), hydroxyethylene glycol ethers of monoand dialkylphenols having 5 l5 ethylene oxide radicals per molecule and 8 9 carbon atoms in the alkyl radical, ligninsulphonic acid, alkali metal and alkaline-earth metal salts thereof, polyethylene glycol ethers (carbowaxes), fatty alcohol polyglycol ethers having 5 ethylene oxide radicals per molecule and 8 to 18 carbon atoms in the fatty alcohol moiety, condensation products of ethylene oxide, propylene oxide, polyvinylpyrrolidones, polyvinyl alcohols, condensation products of urea-formaldehyde, as well as latex products. The active substances are so mixed, ground, sieved and strained with the abovementioned additives that the solid constituent in the case of wettable powders has a particle size not exceeding 0.02 to 0.04 mm, and in the case of pastes not exceeding 0.03 mm.

Emulsion concentrates and pastes are prepared by application of the dispersing agents such as thosementioned in the preceding paragraphs, organic solvents and water. Suitable solvents are,'e.g. the following: ketones, benzene, xylenes, toluene, dimethyl'sulphoxide, and mineral oil fractions boiling in the range of 120 to 350. The solvents must be practically odourless, nonphytotoxic, and inert to the active substances.

Furthermore, the agents according to the invention can be employed in the form of solutions. For this purpose, the active substance (or several active substances) of-the general formula I is (or are) dissolved in suitable organic solvents, solvent mixtures, or water. Thefollowing can be used as organic solvents: aliphatic and aromatic hydrocarbons, chlorinated derivatives thereof, alkylnaphthalenes, or mineral oils on their own or in admixture with each other. The solutions should contain the active substances in a concentration range of from 1 to 20%.

The solid preparations, such as dusts, scattering agents and granulates, contain solid carriers such as those mentioned in the foregoing, and, optionally, additives stabilising the active substance. The particle size of the carriers is for dusts advantageously up to about 0.1 mm; for scattering agents from about 0.075 mm to 0.2 mm; and for granulates 0.2 mm or coarser. The concentrations of active substance in the solid preparations are from 0.5 to

All the mentioned active substance concentrates may also contain agents stabilising against the effects of light, and antioxidants.

Granulate Wettable powder The following constituents are used for the preparation of(a) a 40%, (b) a 50%, (c) a 25%, and (d) a 10% wettable powder:

40 parts of 2-chloroethyl-tris-(ethoxy)-silane,

5 parts of sodium lignin sulphonate,

1 part of sodium dibutylmaphthalene sulphonate, 54 parts of silicic acid;

50 parts of 2-chloroethyl-tris-( ethoxy)-silane,

5 parts of alkylaryl sulphonate (Tinovetin B),

10 parts of calcium lignin sulphonate,

1 part of Champagne chalk/hydroxyethyl cellulose mixture (1 l),

20 parts of silicic acid,

14 parts of kaolin;

25 parts of 2-chloroethyl-tris-(ethoxy)-silane, 5 parts of the sodium salt of the oleylmethyl tauride,

2.5 parts of naphthalenesulphonic acid/formaldehyde condensate,

0.5 parts of carboxymethyl cellulose,

5 parts of neutral potassium aluminium silicate, 62 parts of kaolin;

10 parts of 2-chloroethyl-tris-(ethoxy)-silane, 3 parts of a mixture of the sodium salts of saturated fatty alcohol sulphates, 5 parts of naphthalenesulphonic acid/formaldehyde condensate, 82 parts of kaolin. v The active substances are intimately mixed, in suitable mixers, with the additives; the mixture is subsequently ground in suitable mills and rollers. Wettable powders are thus obtained which can be diluted with water to give suspensions of any desired concentration. Such suspensions are employed, e.g. for the removal of undesired side shoots,-for the tillering of lawns and for the rooting of seedlings and cuttings, etc. 1

Emulsion concentrate The following constituents are mixed together to produce 25% emulsion concentrates:

25 parts of 2-cl'iloro'ethyl-tris-(ethoxy)-silane,

' 5 parts of a mixture of nonylphenolpolyoxyethylene and calcium-dode'cylbenzene sulphonate, 70 parts of sylene;

25 parts of 2chloroethyl-tris-(ethoxy)-silane,

10 parts of a mixture of nonylphenolpolyoxyethylene and calcium-dodecylbenzene sulphonate, 65parts of cyclohexanone.

This concentrate can be diluted with water to obtain emulsions of any desired concentration. Such emulsions are suitable for the thinning out of blossom and fruit, for the accelerated ripening of fruits, and for the promotion of fruit abscission. Compounds of the formula -Continued (iii,

Cl-CH -CH Si-OCO-R o co R,

physical data R1 R4 bp. C/Torr 33 n-C H-, CH 1 /3 34 Cl-CH,CH Si-OCH bp 68C/l6 Performance Characteristics Concentration I The active substances of this invention were sub Activesubstance (ppm) olive Fan (7:) ected to a variety of performance determinations. Performance characteristics of controls and the following comm! 5 Leasure et al. prior art compounds were also deter- 838 2? mined 20 2000 58 A bromoethyl-d1methoxy-methyl silane 20 4000 88 B chloromethyl-diethoxy-methyl silane 23 2000 80 c chloromethyl-diethoxy-methyl silane D chloromethyl-diisopropoxy-methyl silane 24 4000 100 E a-chloroethyl-d1methoxy-methyl silane a. Test on olives On olive trees of the variety CORATINA a number of branches were sprayed, about 1 week before their expected harvest, with aqueous compositions of the listed active ingredients. The concentration of the active ingredients in the spray liquid was always 2000 ppm and each treatment was repeated twice. On each tree, some branches were not treated and served as control branches. The tests were evaluated 4 days after spraying, by shaking the treated and untreated branches by hand. The olives which fell were counted as percent of the initial number of olives on the corresponding branches, and the results are given in the following table:

active ingredient olive-fall 2000 ppm mUO control (untreated) b. Olives 0. Apple Abscission Apple trees of the variety GOLDEN DELICIOUS reduction of average abscission force in active ingredient 4000 ppm control 0% (1. Apple and Peach Thinning Apple trees of the variety GOLDEN DELICIOUS and peach trees of the variety EARLY GOLDEN were sprayed, subsequent to blossom fall, with aqueous compositions of varying concentrations of active substance. Several trees were retained as controls. At the time of application, the young fruit was counted. Two months later, count was taken of the remaining fruit. These results appear in the following table.

In addition, the fruit on the treated trees was large and readily marketable in contrast to the fruit on the untreated trees which was thin and unpalatable.

Remaining Fruit ("/2) Apples Peaches Concentration Active Substance (ppm) Control e. Orange Abscission It was determined in the case of citrus fruits oranges that the abscission of fruit is appreciable easier after application of the active substances of formula I. Various active substances were sprayed, in the form of solutions in concentrations of 0.2 0.4%, on to branches,

well hung with fruit, of various organe trees. The tests were evaluated after 14 days according to the method developed by W. C. Wilson and C. H. Hendershott, cp. Proc. Am. Soc. Hort. Sc. 90, 123-129 (1967). The test consists of measuring the force in kg required for the abscission of the fruit.

Active substance: Concentration Force in kg 2-chloroethyl-tris-( ethoxy 4.5 silane l.5

Furthermore, three different crops of navel oranges were tested by spraying, one week prior to anticipated ripening, branches well hung with fruit, with solutions in concentrations of 1000, 2000 and 4000 ppm of active substance, respectively. Various branches were retained as controls. The tests were evaluated one week after application by measuring the force in kg required for the abscission of the fruit, these results appearing in the following table.

Concentration (p Crop 2 Force( kg) Crop 3 Force( kg) Active Substance Crop l Force(kg) Control f. Tomato Ripening 6 Fully grown but still green tomatoes of the SELMA variety were plucked and dipped for a period of 60 seconds in an aqueous bath containing 3000 ppm of active substance. Twenty tomatoes were included in a test 6 batch. The control tomatoes were contacted only with water. Six days after dipping, the tomatoes were observed in order to determine the number that had reached full ripeness (red). These results are presented in the following table.

Active Substance 7r Ripe Tomatoes Control 25 E 40 l 50 2 50 4 g. Latex Discharge Caoutchouc rubber trees were fitted with a tapping system. A 10% active substance solution in palm oil was then applied to a 5 centimeter wide band of cut bark beneath the tapping cut. Each test sample and control contained ten trees. Thereafter for a period of 2 months, the exuded latex was tapped every second day. The total amount of recovered latex is noted in the following table.

Dry Rubber Recovered Recovered Latex Above Control Active Substance (grams/tree) (grams/tree) Control 231 L2 0 h. Latex Discharge Active substance Grams resin 2-bromoethyl-tris( ethoxy silane 0.37 Control 0 The results establish a clear pattern of excellent performance and a significant improvement over the compounds of the Leasure references.

What is claimed is:

l. A method for regulating the growth of plants as to facilitate fruit abscission which comprises applying to said plants a fruit-abscising amount of a compound of the formula 4. The method of claim 1 in which the abscission of wherein X is chlorine or bromine; Y is a group OR citrus f it i f i|itat and each of R2 and R3 is an alkyl radical having 1 5. The method of claim l in which the abscission of to 5 carbon atoms a les is facilitated 2. The method of claim 1 in which the abscission of 5 PP 6. The method of claim 1, wherein said compound is olives is facilitated.

3. The method of claim 1, wherein said compound is Y y)- 2-chloroethyl-tris-(ethoxy)-silane.

UNITED STATES PATENT AND'TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT N0. 3,912,493

DATED October 14, 1975 |NVENT0R(5) Werner Foery, Hans Peter Fischer it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: 0

The following should be inserted in the heading:

Foreign Application Priority Data 6, switzerlandueveron-e---....-.l4797/70 May 14, 1971 Switzerland. .7206/71 Q Signed and Scaled this sixteenth Day of March 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner nfPatents and Trademarks 

1. A METHOD FOR REGULATING THE GROWTH OF PLANTS AS TO FACILITATE FRUIT ABSCISSION WHICH COMPRISES APPLYING TO SAID PLANTS A FRUIT-ABSCISING AMOUNT OF A COMPOUND OF THE FORMULA
 2. The method of claim 1 in which the abscission of olives is facilitated.
 3. The method of claim 1, wherein said compound is 2-chloroethyl-tris-(ethoxy)-silane.
 4. The method of claim 1 in which the abscission of citrus fruits is facilitated.
 5. The method of claim 1 in which the abscission of apples is facilitated.
 6. The method of claim 1, wherein said compound is 2-chloroethyl-tris-(methoxy)-silane. 